In order to tranform business from a digital aspect, many businesses (medium or large) opt for Google Analytics. Furthermore, it is a superb tool for enlarging the capability of your online presence.

However, there are 3 open source applications alternative to Google Analytics i.e. Piwik, Open Web Analytics and eAnalytics. For more information about these tools, kindly visit : https://opensource.com/business/14/10/top-3-open-source-alternatives-google-analytics

For analyzing your site's traffic I would recommend Clicky, Piwik (self hosted), Google Analytics (free but limited). Try to study those web analytics tools for you to find the most appropriate for your brand.

For every such tool you need to update their code in to your website, because without their tracking code, tools are unable to fetch visitors data on your website. Alexa provides traffic report on your website but for deep you need to have it's paid version.